Variationist/evolutionary models of phonology assume a causal chain that links biases at the utterance level to the development and consolidation of abstract phonological patterns over time. Some of the properties of linguistic cognition that have been proposed to underlie this chain are (i) storage of experienced detail at multiple levels of description, (ii) feedback between perception and production, (iii) a similarity bias in the production and perception of variation, and (iv) enhancement of cues to potentially ambiguous lexical items in usage. I review evidence for these properties and argue that they interact to provide a pathway for individual usage events to influence the evolution of contrastive sublexcal category systems, i.e phoneme inventories. Specifically, the proposed Network-Feedback model predicts that the organization of sublexical category systems is shaped by a conflict between a general drive toward greater similarity among sublexical categories on the one hand, and a bias toward maintaining contrast between tokens of competing lexical categories on the other. The model provides testable hypotheses about the conditions favoring phoneme merger, chain-shifts, and phonemic splits, and more generally about the influence of lexical contrast on the packing of sublexical categories along gestural/perceptual dimensions. Finally, this pathway of change is consistent with proposals that sublexical categories such as features and segments are not primitives of language, but emerge through more general properties of performance, perception, categorization and learning.